Table mounted cutting tools, such as table saws, are valuable tools used for a variety of tasks, such as cross-cutting wood, and ripping large boards or panels into narrow strips. While there are a variety of table saw designs, most table saws include a base housing structure that supports a table top and a cutting assembly positioned below the table top. The table top has a substantially planar upper surface upon which workpieces may be supported.
The cutting assembly includes a circular saw blade that is mounted on an arbor with a portion of the blade extending upwardly through an opening defined in the table top. The cutting assembly also includes a motor with power train for rotating the arbor so that the cutting blade may be driven to perform cutting operations on workpieces supported on the table top. As the motor drives the cutting blade to rotate, a workpiece may be moved across the table top against the blade to allow the blade cut the workpiece.
Motors in table saws typically rotate at a speed that is greater than the speed at which a saw blade can be driven. For instance, a table saw motor may rotate at a speed of between 24,000 and 30,000 RPM, while the saw blade may have an output speed of between 3,500 and 5,000 RPM. Thus, the table saws typically include a power train between the motor output shaft and the saw blade output shaft that reduces the speed.
In a conventional table saw power train, a single stage gear reduction is used to reduce the motor speed to the output shaft speed. A pinion gear fixed to the motor output shaft rotates a driven gear that is fixed to the saw blade output shaft, or arbor shaft. In order to reduce the speed by the required amount, the size of the driven gear must have a considerably larger number of gear teeth than the motor pinion gear. As a result, the driven gear has a relatively large diameter.
The large driven gear, and the housing that encloses it, therefore occupy space above the central axis of the arbor shaft. As a result, the large driven gear limits the uppermost position at which the saw can be positioned. A table saw that has a smaller driven gear on the saw output or arbor shaft would therefore be desirable.